Hi angel,
Welcome to the group, not good you had to be here but it is a great place to learn and get support. I don't think you can stop yourself from getting the flu, the thing is you will probably come in contact with a lot of things that you can catch. How will this effect you count? it is really hard to say some it effects, some not. I have had three major surgery since having ITP and for a few weeks after the surgery my counts where in the 200's and a normal good count for me is around 100 to 140, the reason for this I don't know.
I was on prednisone for ten months, mostly between 40 and 75 mg and I work in the public, coming in contact with 100's of people everyday and I didn't catch a thing but I don't seem to catch flu's very often anyway.
I can understand why your husband is cautious and mine husband is always concerned as well, but as time has gone on he has learned to relax a little and hopefully this will happen to you as well.
I really feel for the families of people with ITP it must be hard for them. I hope ypur counts today are good and you can get of the steroids soon.
There is no practice run in life.